And I'm Steve Inskeep. This week's gathering of world leaders at the United Nations General Assembly coincides with at least three world crises.

GREENE: One is the assault on a mall in Kenya. Another is Syria's war and the use of chemical weapons there. The third: the world confrontation with Iran and Iran's introduction of a new president.

INSKEEP: At this hour, President Obama is speaking to the U.N. General Assembly. Earlier we spoke with NPR's Ari Shapiro, who's in New York, about what the president is focusing on. Hi, Ari.

ARI SHAPIRO, BYLINE: Morning, Steve.

INSKEEP: The president expected to cover all of that?

SHAPIRO: Yeah, all of it and then some. For example, on Syria he's expected to talk about the need to get rid of Bashar al Assad's stock of chemical weapons and somehow resolve this conflict that has now killed more than 100,000 people. On Iran he'll talk about the potential for progress on that country's nuclear program and the overtures that Iran's new president has made reaching out to the West.

He'll also talk about Mideast peace, which is a subject he often discusses at the U.N., but this time it comes as Palestinians and Israelis are actually negotiating for the first time in years. So there seems to be some glimmer of potential there. And finally we expect him to talk of course about the attack on that shopping mall in Kenya.

It's a subject he mentioned in his first meeting here in New York yesterday, where he promised to support the Kenyan people and also work with the international community to dismantle terrorist networks.

INSKEEP: OK. So much to discuss there. But let's talk a little bit about Syria, Ari Shapiro, because the president's at the U.N. The U.N. has been put on the spot. Russia's President Vladimir Putin was scolding the United States for not going through the U.N. when they were threatening strikes on Syria, and of course Russia has also been blocking the U.N. from acting on Syria. So what can the U.N. do now?

SHAPIRO: Yes, exactly. Well, now the U.S. and Russia have this agreement to get Syrian president Bashar al Assad to give up his chemical weapons. The question is whether the U.N. Security Council will pass a resolution to make that agreement legally binding, enforceable if Syria does not live up to its end of the bargain. So the question is, what does enforceable mean? The U.S. would like it to include military action, Russia would not.

And so that's the push-pull that we're seeing play out this week on Syria at the U.N.

INSKEEP: So we still don't know if the U.N. will be able to act in a way that everyone agrees is concrete. That's still undecided.

SHAPIRO: Still undecided whether the Security Council will be able to do something or whether Russia will block it again.

INSKEEP: OK. And so we have that going on. And we have this kind of symbolic drama involving Iran, because there's a new Iranian president, Hassan Rohani, who's in New York. Will he meet President Obama?

SHAPIRO: Unclear. We know that the two presidents have been sort of pen pals. They've been writing letters to each other. Rohani has sent lots of signals that he wants to chart a different course from his predecessor. He wrote an op ed in the Washington Post saying it's time to engage. But the White House has been very coy about whether Obama will meet with Rohani.

Aides keep saying they are open to engagement but nothing is on the schedule. No U.S. president has met with an Iranian president since before the Iranian revolution in 1979. So a meeting of that sort would be huge. The countries did arrange for Secretary of State John Kerry to meet his Iranian counterpart. In a briefing yesterday somebody asked, well, if Presidents Rohani and Obama do end up crossing paths and shaking hands, would that be happenstance?

And the White House aide who answered, Ben Rhodes, said: I don't think anything would happen by happenstance on a relationship and issue that is this important.

INSKEEP: OK. So there's not a meeting on the schedule, on the agenda, with the Iranian president. What is on President Obama's agenda after this speech?

SHAPIRO: Well, later this afternoon the president turns his attention to domestic affairs. He is going to meet with President Clinton live on stage and the two are going to discuss the Affordable Care Act, or Obamacare. Signups are scheduled to begin October 1, and the White House says this sort of informal conversation between the two presidents about the healthcare law is going to launch an intensive six month push.

This follows on a speech that President Clinton recently gave where he urged Republicans to stop trying to repeal the law and focus on ways to improve it. It shows here that the former president has become a key salesman in pitching this law to the American people.

INSKEEP: Of course Republicans are trying to defund Obamacare in connection with the possibility of a government shutdown this week. Do you have any sense the president is glad to be out of Washington and leaving the Republicans to struggle with their own plan?